Hydrometer



March I26, 1940. `G K, PORTER 2,-195,339

HYDROMETER Filed Jan. 2'7, 1936 ffflvorr aktor/Mg Patented Mar; 2 6, 1940 i HYDBOMETER George K. Porter; Philadelphia. Pa., assignor, by ,mesne, assignments. to American 'Instrument Company, Silver,Spring,Md., a copartnership i v composed of William H. Reynolds and Leopold.l el

Freedman I application January 27, 1936. Serial No. 61,068. tonene. -(o1. 2cs+4s) This` invention relatesl tofqhydrometers. for measuring'j the [density of liquids andr among other. objects, aims to provide animproved vhydrometer of the type having a glassballast cham- '59' ber fused to or integrally united with the lower end of the float'chamber and so constructedr that the stresses in, the glass. caused by the fus-' ing and sealing operations in the process of manufacture of 'the instrument, are' distributed throughout thewalls yof the ballast chamber and willv notcause the chamber to crack or break after the instrumentis used for a period of time. The idea is to provide an elonga'ted, bulbous, ballast chamber,` secured intermediate its ends to the lower end of vthe float chamber so as to perg mit some expansion and contraetion of the glass at the fused joint without cracking the float chamber.

Other aims and., advantages of the invention o will appear in the specificationwhen considered f in connection with one embodiment of the invention illustrated in the accompanying drawing, I wherein: j

Fig. 11 is anelevation disclosing a step in the 5 preferred methodof making the instrument;

Fig. 2 is a similar view showing another step,

' parts being shown in section; 4

' Fig. 3 is aV similar view showing the ballast chamber after it islformed or shaped;V i o Fig. 4 is la similar view showing the, ballast chamber temporarily sealed oif and the ballast flplaced in the'float chamber readyv forv rough calibration of the'instrument; and i i Fig. 5 is an elevation of the completed instruv ment. i `It has been found in practice' that hydrometers having ballast Chambers formed of glassand i fused to the bottom of the 'float chamber,V such as are shown in'* the patent to Hiegersell No. 1,610,616, aresubject to cracking strains'caused by the heat applied to the glass during the sealing, Opening and resealing operations on the end of the ballast chamber.V Theheat of fusion in these operations is conducted to the joint at the 5v end of thel float chamber and a glass diskkwllfv prevent any vrelative expansion or .contractioni' 5 lincreased areavof glass in` the upper end of the v ballast chamber through which the Ystresses are distributed. f

vReferring Vparticularlyto the drawing, the instrument there. shown for illustratve purposes g has a` bulbo-us'ballast chamber in the form of a 5.

double cone,*whih is the preferred fcommercial design. Fig; 1 showsone of the first'steps in thevmanufacture of an instrument of this type. In this instance, there is shown a cone `I!! formed on one end of a glass .tube Hv which is of the same diameter as' the tubej|2 which. forms the cylindrical float chamber. This cone is formed in the usual manner by theordinary glass blowing operations. It is then inserted in'the open lower endof vthe float chamber'tube 'l2` and fused to said tube to provide a fused joint l3 around the base of the cone. While the'fused joint and the parts adjacent to itvare still (hot, the tube `I I vbelow the end of the float chamber is'drawn'and shaped rto form a bottom cone M havingja -tail mg I 5, the waste portion of the tube l l being broken oif. I Obviously, the double cone may be formed before it is joined to the float chamber. but the above described method'is preferred. In this'` condition, the fused-on double cone is annealed 254 in an oven to relieve the joint and the portions of the double cone'and float chamber adjacent thereto of destructive Cracking strains. .An open stem IB of the desired vlength is. fused on vthe upper end of the float chamber in the usual man- 3 ner.

The instrument is now ready tol be roughly calibrated. This is done as shown in Fig; 4, byl i sealing oif theballast chamber. The' lower end of the cone [4 is sealed in a fiame and'the' tail '85 l5 is pulled off; then,` thevmercury ballast ll is introduced into the float chamber throughthe i open stem; The weight` of mercury is :determined 'by adding it until thelower portion of the stem is submerged and the zero calibration is at the desired point'on the stem.r Then, the mercury is 'removed from the float chamber and in- ;troduced into the ballast chamber 'by'reopening theballast chamberl in a flame and, then, re-

sealing it by refusing the Opening in lthe tip of the lower cone. The instrument is then-completed by finally calibrating itv and inserting the -jusual paper scale in the stem andj-thereafter, "sealing the upper end of'the stem. '3 From the foregoing description, it will lbe ob-I j served that'` the ballast. chamber'is vformed'of a lunitary mass of glass and there is only one fused joint lat, its junction with the float-"chamber;

Moreover, the upper cone lo within'thewfloat i chamber presents a much greaterglascsarea than I g the lower end of the float chamber on the inside lower end of the fioat chamberto provide apartition, as in the aforesaid patent. It has been 'found in practice that instruments of this type will stand a, great dealmore abuse than instruments made according to the aforesaid patent and that they do not crack or break due to any inherent strains or stresses induced in the glass by conduction of heat when the ballast chamber is finally sealed off. Since theballast chamber is in the form of an elongated bulb fused intermediate its ends to the fioat chamber, the fused joint can expand and contract slightly to prevent 'the float chamber wall from cracking` at or near the joint. i

Obviously, the present nvention is not limited to the particular embodiment thereof herein shown and descrbed. Neither is it dependent upon the particular method of producingvit because it can be made in accordance With many other methods which will readily Suggest themselves to those skilled in the art of glass'wor'king'.

What is claimed is:

1. In a hydrometer of the character described havnga glassfioat chamber, a closed elongated, bulbous-ballast chamber united intermediate its ends to the lower end lof the'fioat chamber, the upper portion of said ballast chamberextending into the fioat chamber and decreasing in size upwardly from the point of union. i

2. In a hydrometer-having a cylindrical, glass fioat chamber, a double, conical, glass, ballast chamber fused at the junction of the cones to thereof and sealedto confine the ballast therein.

3. In a glass hydrometer having a cylindrical fioat chamber, a closed-` elongated, bulbous, ballast chamber composed of a single piece of glass having tapered upper and lowerends, `said chamber being` fused, intermediateitsends, within the lower end of the fioat chamber."

4. In a .hydrometer of 'the character described having a fioat chamber, aclose'd ballast cham-` ber integrally united, intermediate its ends, to the lower end of the float chamber and having a hollow, Vconical portion projecting upwardly into the fioat chamber above the union.-

5. A glass hydrometer co'mprisnga cylindrical I wall forming a hollow chambenfa hollow stem atthe chamber formed by said `(gone-like members.

' 6. In an article of manufacture of glass, comprising a cylindrical wall of glass, two hollow conelike members having their bases fused together forming a sealed chamber, rsaid bases also being fused to one-end of the cylindrical wall of glass, and a liquid ballast trapped within the chamber formed by said cone-like'members.

- GEORG-E K. PORTER. 

